For many years, parachutes have been used for the final flight and recovery stage of spacecraft, target drones, camera film, and similar items. A problem with ordinary parachutes, circular or conical design, is that they descend almost vertically through the relative airstream and consequently are carried generally with the wind. This makes the landing point highly uncertain. Additionally, the rate of descent is in the order of fifteen to twenty-five feet per second. This results in a fairly rough landing on solid surfaces. As a result, most of these landings have been conducted on water. These water landings involve other complexities, such as auxiliary flotation devices, to keep the payload from sinking. The water landings also require that the payloads be of a type that cannot be damaged by water or must be of a type that are protected against damage by water.
Ram-air inflated parachutes, such as those used by sports sky divers, are able to move horizontally as much as three or four feet for every foot of vertical descent. This allows the parachutes to make headway into a fairly stiff wind of up to twenty or thirty knots. Additionally, these ram-air inflated parachutes are steerable so as to allow a pilot to select a landing spot with substantial precision. For instance, sport jumpers commonly land within a few feet of their selected targets. The ram-air parachutes also have the ability to "flare" before a landing. This makes it possible to reduce both forward speed and the rate of vertical descent in the last few seconds beofre touchdown. Under the control of a competent pilot, these ram-air parachutes can make a much more precise and gentle touchdown than an ordinary circular parachute.
Ram-air parachutes are steered by pulling down about two feet on a pair of steering toggles which lower trailing edge flaps at the rear of the canopy. Pulling down on the right flap steers the canopy to the right and pulling down on the left flap steers the canopy to the left. The pulling of both flaps simultaneously results in the flare. This reduces forward speed and vertical descent rate simultaneously for a short period time. A ram-air parachute can be controlled by an on-board pilot or can be controlled by servo motors operated by radio or on-board auto-pilots. Such servo motor controlled ram-air parachutes can also be assisted by an on-board computer. The final flare and touchdown can be facilitated by an on-board radar altimeter.
Several prior-art United States patents show various parachute systems for mid-air load recovery. U.S. Pat. No. 2,942,815, issued to R. J. Gross et al., on June 28, 1960, describes an apparatus for retrieving objects descending by parachute. The parachute used in this invention is of the standard circular design. This parachute has a plurality of cone-shaped extensions extending outwardly beyond the canopy of the parachute. A retrieving line extends between the points of each of these cone-shaped extensions. A grappling hook utilized by an aircraft serves to connect with this line.
U.S. Pat. No. 3,137,465, issued to G.R. Mulcahy, Jr., on June 16, 1964, discloses a load recovery parachute system. In this system, a drogue parachute is released from the top of the standard circular parachute. A helicopter with an extending hook intercepts the drogue parachute. After intercepting the drogue parachute, the main parachute collapses and the load is carried by the intercepting helicopter.
U.S. Pat. No. 3,389,880, issued on June 25, 1968, and Reissue Pat. No. 26,865, issued on Apr. 21, 1970, to O. B. Ferguson, disclose another type of parachute system for mid-air load recovery. This system also utilizes a drogue parachute that is released outwardly from the top of a standard circular parachute. A helicopter then engages the lines of a drogue parachute so as to intercept the descending object. The drogue parachute is designed so as to enhance the ability of the grappling hook to engage the drogue parachute.
Each of these prior-art patents utilizes the standard circular-type of parachute. As stated previously, the problem with the standard parachutes is that the rate of vertical descent is much greater than the rate of horizontal movement. In order for a helicopter to intercept such a parachute, the helicopter must descend toward the parachute and descend through the helicopter's prop wash. This would create a significant amount of turbulence for the helicopter and make the task of engaging the parachute a difficult task. In order for a helicopter to descend at the rate of the standard circular-type parachute, the helicopter will have to assume a "power shutoff" situation. The helicopter will descend at the rate of the parachute when power is disengaged from the helicopter blades. Unfortunately, this is not an optimal situation for the pilot of the helicopter or for the purpose of intercepting the descending object. It is preferably for the helicopter to be moving horizontally at a much lower rate of descent than would be provided by these prior-art patented systems.
It is an object of the present invention to provide an aerial recovery system which enhances the ability of a helicopter to retrieve the load.
It is another object of the present invention to provide an aerial recovery system which provides a large target for interception.
It is another object of the present invention to provide an aerial recovery system which eliminates the need for water landings.
It is still a further object of the present invention to provide an aerial recovery system that reduces the risk of damage to the descending object.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.